It relates in general to the field of cements and concretes and more specifically to cements and concretes based on yttrium and the lanthanides. Cements based upon oxides are useful in a variety of applications because of their refractory nature and resistance to high temperature interactions with metals, carbon and other refractories. Cements and concretes based on yttrium oxide are particularly useful in melting and casting operations because they do not contaminate or react with molten reactive metals such as uranium. Concretes and cements based on europium oxide and gadolinium oxide are useful as neutron absorbers for reactor applications. Other lanthanide oxide cements are useful in general fabrication technology for making ceramic ware resistant to high temperatures.